Hot wall rapid thermal processor

ABSTRACT

An apparatus for heat treatment of a wafer is disclosed. The apparatus includes a heating chamber having a heat source. A cooling chamber is positioned adjacent to the heating chamber and includes a cooling source. A wafer holder is configured to move between the cooling chamber and the heating chamber through a passageway and one or more shutters defines the size of the passageway. The one or more shutters are movable between an open position where the wafer holder can pass through the passageway and an obstructing position which defines a passageway which is smaller than the passageway defined when the shutter is in the open position.

RELATIONSHIP TO CO-PENDING APPLICATIONS

This application is a continuation-in-part of Provisional U.S.application Ser. No.: 60/096,283; filed on Aug. 12, 1998; entitled“Linear RTP Reactor” and incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for providing heat towafers and more particularly to an apparatus for rapid thermalprecessing of wafers.

2. Description of Related Art

Heat treatment apparatuses are used in a variety of industries includingthe manufacture of semiconductor devices. These heat treatmentapparatuses can be used for several different fabrication processes suchas thermal annealing, thermal cleaning, thermal chemical vapordeposition, thermal oxidation and thermal nitridation. These treatmentsoften require that the temperature of a wafer be elevated to as high as350° C.-1300° C. before and during the treatment. Further, thesetreatments often require that one or more fluids be delivered to thewafer.

There are several design challenges to meeting the thermal requirementsof heat treatment apparatuses. For instance, it is often desirable toquickly ramp up and/or ramp down the temperature of a wafer to betreated. During these rapid temperature changes the temperatureuniformity of the wafer should be sufficient to prevent damage to thewafer. Wafers often cannot tolerate even small temperature differentialsduring high temperature processing. For instance, a temperaturedifference above 1°-2° C./cm at 1200° C. can cause enough stress toproduce slip in the silicon crystal of certain wafers. The resultingslip planes will destroy any devices through which they pass.

Delivery of fluid to the wafer can also present design challenges. Forinstance, the exposure of the wafer to the fluid should be uniformacross the wafer to avoid uneven treatment results. Further, fluidswithin the heat treatment apparatus must often be rapidly evacuated fromthe heat treatment apparatus. Another challenge derived from fluiddelivery is the replacement of fluids within the heating chamber withother fluids. This exchange of fluids must often occur with minimalinteraction between the original and replacement fluids.

SUMMARY OF THE INVENTION

The invention relates to a heat treatment apparatus. The apparatusincludes a heating chamber having a heat source. A cooling chamber ispositioned adjacent to the heating chamber and includes a coolingsource. A wafer holder is configured to move between the cooling chamberand the heating chamber through a passageway. One or more shuttersdefine the size of the passageway and are movable between an openposition where the wafer holder can pass through the passageway and anobstructing position which defines a passageway which is smaller thanthe passageway defined when the shutter is in the open position.

Another embodiment of the apparatus includes a heating chamberpositioned adjacent to a cooling chamber. A wafer holder is configuredto be positioned in the cooling chamber at a loading position where thewafer can be removed from the wafer holder. The wafer holder is movablebetween the cooling chamber and the heating chamber. A cooling sourcesuch as a cooling plate is positioned in the cooling chamber so as to bepositioned beneath the wafer holder when the wafer holder is positionedin the loading position.

Another embodiment of the apparatus includes a heating chamber with aclosed upper end. A plurality of heating elements are positioned abovethe closed upper end of the heating chamber. The upper end of theheating chamber includes a heating plate which is configured to receivethermal energy from the heating elements and distribute the thermalenergy in a substantially uniform manner over a surface of the heatingplate which is positioned within the heating chamber. The heating plateincludes a plurality of fluid ports which are configured to be coupledwith a fluid source. A wafer holder is configured to be positioned inthe heating chamber such that a wafer held by the wafer holder receivesfluid delivered into the heating chamber through the fluid ports.

Another embodiment of the apparatus includes a cooling chamberpositioned adjacent to a heating chamber. A wafer holder is coupled withat least one shaft which is driven so as to move the wafer holderbetween the cooling chamber and the heating chamber through apassageway. Two or more shutters are positioned adjacent to thepassageway and are movable within a horizontal plane so as to define thesize of the passageway. The two or more shutters are movable to anobstructing position where the two or more shutters encompass the atleast one shaft coupled with the wafer holder.

The invention also relates to a heat treatment apparatus having aheating chamber and one or more fluid inlet ports for delivery of afluid into the heating chamber. A member extends into the heatingchamber from a side of the heating chamber at a height below a height ofthe fluid inlet port. The member has an edge with a shape which iscomplementary to the perimeter of a portion of the wafer to be treatedin the apparatus. A wafer holder is movable within the heating chamberand can move the wafer adjacent to the member to define a fluid flowregion within the heating chamber.

Another embodiment of a heat treatment apparatus having a heatingchamber and one or more fluid inlet ports for delivery of a fluid intothe heating chamber includes a flow distribution chamber whichdistributes a flow of fluid from the one or more fluid inlet ports. Theflow distribution chamber is positioned such that fluid from the fluidinlet port enters the heating chamber through the flow distributionchamber.

The apparatus can also include a fluid exhaust port for withdrawingfluid from the heating chamber and a second flow distribution chamberfor distributing a flow of fluid from the heating chamber to the fluidexhaust port. The second flow distribution chamber is positioned suchthat fluid from the heating chamber enters the fluid exhaust portthrough the flow distribution chamber.

A flow distribution chamber associated with a fluid inlet port caninclude a flow distribution member positioned such that fluid from thefluid inlet port enters the heating chamber through the flowdistribution chamber. Similarly, a flow distribution chamber associatedwith a fluid exhaust port can include a flow distribution memberpositioned such that fluid from the heating chamber enters the fluidexhaust port through the flow distribution chamber.

The invention also relates to a method for rapid thermal processing of awafer. The method includes providing a heating chamber having a heatingplate and heating the heating plate. The method also includespositioning a wafer in a wafer holder and moving the wafer holder towardthe heating plate until the wafer is positioned close enough to the heatsource for heat to be conducted from the heating plate to the wafer.

The method can also include backing the wafer holder away from theheating plate after a target condition has been achieved at the waferand delivering a fluid into the heating chamber from above the waferholder.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a cross section of a heat treatment apparatus having aheating chamber adjacent to a cooling chamber.

FIG. 1B is a cross section of a heat treatment apparatus having ashutter in an open position.

FIG. 1C is a cross section of a heat treatment apparatus having ashutter in an obstructing position.

FIG. 2A is a cross section of a heating chamber having a heating platepositioned outside a processing tube.

FIG. 2B is a cross section of a heating chamber having a heating platepositioned inside a processing tube.

FIG. 3 is a cross section of a cooling chamber having a cooling fluidconduit for delivering a cooling fluid to a wafer.

FIG. 4A is a bottom view of an upper end of a heating chamber. Aplurality of fluid ports are formed in the upper end.

FIG. 4B is a cross section of an upper end of a heating chamber. Theupper end includes a lumen coupled with a plurality of fluid ports.

FIG. 4C is a cross section of an upper end of a heating chamber. Showinga plurality of fluid ports extending through the upper end.

FIG. 5A illustrates a fluid delivery system with a fluid inlet port anda fluid exhaust port positioned to produce a cross flow of fluid withinthe heating chamber.

FIG. 5B illustrates a fluid delivery system with a fluid inlet port anda fluid exhaust port positioned to produce a downward flow of fluidwithin the heating chamber.

FIG. 6A illustrates a fluid delivery system having a flow containmentmember extending into the heating chamber from the processing tube.

FIG. 6B illustrates the fluid delivery system of FIG. 6A in a processingtube with a rounded cross section.

FIG. 6C illustrates the fluid delivery system of FIG. 6A in a processingtube with a rectangular cross section.

FIG. 6D illustrates a fluid delivery system having a plurality of fluidinlet ports and a plurality of fluid exhaust ports.

FIG. 7A illustrates a fluid delivery system with a flow distributionchamber positioned adjacent to a fluid flow region.

FIG. 7B is a sideview of a flow distribution member for use in a flowdistribution chamber.

FIG. 7C illustrates a fluid delivery system having an arc shaped flowdistribution member.

FIG. 7D illustrates a fluid delivery system having a flat flowdistribution member in a round processing tube.

FIG. 7E illustrates a fluid delivery system having a flat flowdistribution member in a rectangular processing tube.

FIG. 8 illustrates a fluid delivery system having a flow containmentmember coupled with a heating plate.

FIGS. 9A-9D illustrate fluid delivery system having a fluid flow passagedefined by a portion of a fluid inlet port, a fluid flow region and aportion of the fluid exhaust region.

FIG. 10A is a cross section of a shutter in an open position.

FIG. 10B is a cross section of a shutter in an obstructing position.

FIG. 11A is a topview of shutters in an obstructing position which ispreferred when a wafer holder is positioned in a heating chamber.

FIG. 11B is a topview of shutters in an obstructing position which ispreferred when a wafer holder is positioned in a cooling chamber.

FIG. 11C is a plan view of a shutter having a recess accommodating ashaft.

FIG. 12A illustrates a plurality of heating elements arranged inconcentric heating zones.

FIG. 12B illustrates heating elements arranged concentrically relativeto one another.

FIG. 12C illustrates thermal isolation barriers arranged between heatingzones.

FIG. 12D illustrate thermal isolation barriers extending from heatingzones toward a processing tube.

FIG. 13 illustrates a shaft conduit extending from a cooling chamber.

FIG. 14 illustrates the relative contributions of heat transfer fromconduction and radiation.

DETAILED DESCRIPTION

The present invention relates to a heat treatment apparatus. The heattreatment apparatus includes a heating chamber with a heating sourcepositioned adjacent to a cooling chamber with a cooling source. Theapparatus also includes a wafer holder configured to be moved betweenthe heating chamber and the cooling chamber through a passageway. Ashutter is positioned to control the size of the passageway. The shuttercan be moved between an open position where the passageway is definedlarge enough for the wafer holder to pass through and a plurality ofobstructing positions where a smaller passageway is defined. The shuttercan be positioned in the obstructing positions whether the wafer holderis positioned within the cooling chamber or within the heating chamber.

The shutter can be constructed as a thermal insulator. Accordingly, whenthe shutter is positioned in an obstructing position, the shutter canserve to increase the thermal isolation between the heating chamber andthe cooling chamber above the degree of thermal isolation which isachievable without the shutter. The increased thermal isolation alsoallows for an increased difference between the average temperaturewithin the heating chamber and the average temperature within thecooling chamber. For instance, for a given average temperature in theheating chamber, the cooling chamber can have a lower averagetemperature than would be possible without the shutter. Reducing theaverage temperature in the cooling chamber permits an increasedtemperatures ramp down rate when the wafer is positioned within thecooling chamber. Similarly, increasing the average temperature in theheating chamber permits increased temperature ramp up rates when thewafer is within the heating chamber. Increasing the temperature ramp upand ramp down rates allows for quicker wafer treatment rates andaccordingly quicker throughput.

The heating source can include a heating plate which receives heat raysfrom heating elements positioned above the heating plate. The heatingplate re-radiates the received heat into the heating chamber from asurface of the heating plate which is positioned within the heatingchamber. The heating plate is constructed from a material with a highthermal conductivity so the received heat has a more uniformdistribution across the heating plate. Increasing the uniformity of thethermal distribution within the heating plate also increases theuniformity of heat rays radiated into the heating chamber.

During the temperature ramp up of the wafer, the wafer holder can bepositioned anywhere within the heating chamber. However, the waferholder is preferably positioned such that a wafer within the waferholder is sufficiently close to the heating plate that heat is conductedfrom the heating plate to the wafer. For instance, the wafer ispreferably positioned within two millimeters of the heating plate. Thispositioning of the wafer relative to the heating plate allows the heattransfer to occur through both conduction and radiation. Since two formsof heat transfer deliver heat to the wafer, the apparatus can increasethe temperature ramp up rate above the temperature ramp up rate achievedby apparatuses relying primarily on radiation as the heat transfermechanism.

The heating plate can define at least a portion of the upper end of theheating chamber and the path from the wafers to the heating plate can beunobstructed. This unobstructed path permits the wafer to be moved incloser proximity to the heating plate. Additionally, the unobstructedpath prevents intervening mediums from altering the uniformity of thethermal distribution of heat produced by the heating plate. Further, theunobstructed path also permits more control over the conditions at thesurface of the wafer. For instance, changes in the conditions of theheating plate, such as changes in the temperature of the heating plate,are transferred directly to the wafer without being delayed by transferthrough some intervening medium.

A relationship between the temperature of the heating plate and thetemperature of the wafer surface can be developed for a particulardisplacement of the wafer from the heating plate. This relationship canbe used to control the temperature of the wafer by adjusting thetemperature of the heating plate. Since the heating plate has a largethermal mass, it acts as a thermal reservoir with a temperature which iseasily monitored and controlled. Since the temperature of the heatingplate is easily controlled, the above relationship allows thetemperature of the wafer to be more easily controlled than is currentlypossible with an infrared pyrometer.

A number of improved fluid delivery systems are included in the scope ofthe present invention. For instance, a plurality of fluid ports can beformed in the upper end of the heating chamber. A fluid can be deliveredinto the heating chamber through these fluid ports. Because these fluidports are positioned at the upper end of the heating chamber, the fluidcan be delivered onto an upper surface of a wafer in the wafer holdereven when the wafer is positioned in close proximity to the upper end ofthe heating chamber. These fluid ports can be uniformly positionedacross the upper end in order to increase the uniformity of the fluiddelivery to the wafer. The increased uniformity allows for a plug typeflow of fluid from the upper end of the heating chamber toward thewafer. A plug type flow allows for a more rapid evacuation of fluid fromthe heating chamber. Further, a plug type flow allows the fluids withinthe heating chamber to be rapidly exchanged with a reduced level ofinteraction between the exchanged gasses.

Since the heating plate can be included in the upper end of the heatingchamber, the fluid ports can be included in the heating plate.Accordingly, the heating plate can be used for delivery of both heat andfluids to the wafer.

The cooling source within the cooling chamber can include a coolingplate. The cooling plate can be positioned so that an upper surface ofthe cooling plate is adjacent to a wafer on the wafer holder when thewafer holder occupies one or more loading positions within the coolingchamber. The loading positions are positions which the wafer holder canoccupy while wafers are loaded and unloaded from the wafer holder. Thecooling plate preferably has a high thermal conductivity so the coolingis distributed through an upper surface of the cooling plate and a highthermal emissivity so the cooling effects are distributed into thecooling chamber. Distribution of the cooling through the cooling plateincreases the uniformity of cooling provided to the wafers andaccordingly reduces the stress experienced by the wafers during cooling.

The cooling source can also include a cooling fluid conduit fordelivering a cooling fluid into the cooling chamber. The cooling fluidconduit can be used instead of a cooling plate or can replace thecooling plate.

FIG. 1A illustrates a cross section of a heat treatment apparatus 10.The apparatus 10 includes a casing 12 which partially encloses a heatingsection 14 of the apparatus 10. The heating section 14 includes one ormore thermal insulators 16 positioned adjacent to a heating chamber 18.A plurality of heating elements 20 are attached to a thermal insulator16 adjacent to an upper end 22 of the heating chamber 18. Suitableheating elements 20 include, but are not limited to, resistive heatingelements coupled with a power source controlled by a computer (notshown).

The heating chamber 18 is partially defined by a processing tube 24. Aheating plate 26 defines the upper end 22 of the heating chamber 18. Theheating plate 26 has a perimeter which is large enough to cover a wafer28 positioned adjacent to the heating plate 26. The heating plate 26 canbe constructed from the same materials as the rest of the processingtube 24 or can be constructed from different materials. Further, theheating plate 26 can be formed integrally with the remainder of theprocessing tube 24 or can be attached to the remainder of the processingtube 24. Suitable materials for the processing tube 24 include, but arenot limited to, high purity quartz, fused silica and silicon carbide.Further, the heating plate 26 is preferably constructed from materialswith a high thermal conductivity such as silicon carbide and graphitecovered with silicon carbide.

The heating plate 26 and heating elements 20 serve as an example of aheat source for use with the apparatus 10. The heating plate 26 receivesheat rays radiated from the heating elements 20 and radiates secondaryheat rays into the heating chamber 18. The heating plate 26 can have ahigh thermal conductivity so the heat received from the heating elements20 is distributed through the heating plate 26. The distribution of theheat through the heating plate 26 causes the heating plate 26 to producea more uniform thermal distribution than the thermal distribution of theheat produced by the heating elements 20.

A plurality of secondary heating elements 30 can optionally be coupledwith the thermal insulators 16 adjacent to the sides of the processingunit. The secondary heating elements 30 can provide additional heat tothe heating chamber 18 and/or can be used to achieve a more accuratecontrol over the temperature within the heating chamber 18.

The apparatus 10 also includes a cooling chamber 32 positioned adjacentthe heating chamber 18. FIG. 1A illustrates a wafer 28 resting on aplurality of wafer support pins 34 extending upward from the bottom ofthe cooling chamber 32. The cooling chamber 32 can be accessed from aload/lock chamber through a slit valve 36 in order to load and/or unloada wafer 28 from the wafer support pins 34. A robotic arm can be used toload and unload the wafer 28 from the pins. Although a single wafer 28is illustrated in FIG. 1A, a cartridge holding a plurality of wafers 28can be supported on the wafer support pins 34. Accordingly, the heattreatment apparatus 10 of the present invention can be used toconcurrently treat a plurality of wafers 28.

FIG. 1A also illustrates a wafer holder 38 in a loading position beneaththe wafer 28. The loading positions are positions occupied by the waferholder 38 when a wafer 28 is loaded on and/or off the wafer support pins34. The wafer holder 38 can have a ring shape which encompasses thepins. As will be described in more detail below, the wafer holder 38 isconfigured to move between the cooling chamber 32 and the heatingchamber 18.

A cooling source 40 is positioned within the cooling chamber 32 so as tobe beneath the wafer holder 38 when the wafer holder 38 is positionedwithin the cooling chamber 32. The cooling source 40 is preferablypositioned adjacent to the bottom of the cooling chamber 32 and is mostpreferably positioned beneath the wafer 28 when the wafer holder 38 isin a loading position.

The cooling source 40 preferably includes a cooling plate 42. Thecooling plate 42 can be positioned adjacent to one or more cooling fluidconduits 44 as illustrated in FIG. 1A. Alternatively, a cooling plate 42can include one or more cooling fluid conduits 44 extending through thecooling plate 42 as illustrated in FIG. 1B. A cooling fluid can beflowed through the cooling fluid conduits 44. The cooling plate 42serves to distribute the cooling effect of these fluids across thesurface of the plate so a wafer 28 being held by the wafer holder 38sees a more uniform cooling effect. Suitable cooling fluids for use withthe cooling fluid conduits 44 include, but are not limited to, chilledwater and liquid nitrogen. Suitable materials for the cooling plate 42include, but are not limited to, materials with a high thermalconductivity and/or a high thermal emissivity such as silicon carbide,aluminum, stainless steel, copper coated with silicon nitride andaluminum nitride.

When the cooling source 40 is a cooling plate 42, the cooling plate 42preferably has a solid upper surface 46 which is substantially parallelto the plane of the wafer 28 in order to provide substantially uniformcooling to the wafer 28. However, the cooling plate 42 can include aplurality of apertures which are large enough to accommodate the wafersupport pills 34 or the wafer support pins 34 can be mounted directly tothe upper surface 46 of the cooling plate 42.

The upper surface 46 of the cooling plate 42 preferably has a perimeterwhich is larger than the perimeter of the wafer 28. Further, the coolingplate 42 is preferably positioned to be approximately concentric withwafers 28 positioned on the wafer support pins 34 or with wafers 28being held by the wafer holder 38. For instance, the cooling plate 42preferably has a round shape with a larger diameter than the wafer 28.The round shape of the cooling plate 42 is then positioned such that thecenter of the cooling plate 42 is positioned approximately beneath thecenter of the wafer 28. This concentric positioning combined with theincreased diameter of the cooling plate 42 relative to the wafer 28causes the perimeter of the cooling plate 42 to extend beyond theperimeter of the wafer 28.

The wafer holder 38 is coupled with a shaft 48. The shaft 48 can becoupled with an elevator mechanism (not shown) which can provide theshaft 48 with an upward and downward motion. The upward motion of theshaft 48 elevates the wafer holder 38 as illustrated in FIG. 1B. Whenthe wafer holder 38 is in a load position as illustrated in FIG. 1A,elevation of the wafer holder 38 lifts the wafer 28 from the wafersupport pins 34 and can move the wafer holder 38 from the coolingchamber 32 to the heating chamber 18. The shaft 48 can also be moveddownward to move the wafer holder 38 from the heating chamber 18 to thecooling chamber 32 and to replace the wafer 28 upon the wafer supportpins 34. Although the wafer holder 38 is illustrated as coupled with asingle shaft 48, the wafer holder 38 can be coupled with a plurality ofshafts 48 including, but not limited to, two, three and four shafts 48.Further, when the apparatus 10 includes a cooling plate 42, the coolingplate 42 can include apertures configured to accommodate each of theshafts 48 coupled with the wafer holder 38.

As illustrated in FIG. 1B, the apparatus 10 includes shutters 52 whichdefine the size of a passageway 54 between the cooling chamber 32 andthe heating chamber 18. The shutters 52 illustrated in FIG. 1B arepositioned in an open position where the shutters 52 define a passageway54 which is sufficiently large for the wafer holder 38 to pass betweenthe heating chamber 18 and the cooling chamber 32.

The shutters 52 can be coupled with motors 56 which serve to move theshutters 52 in a horizontal plane as illustrated by the arrow labeled B.Accordingly, the shutters 52 can be moved to an obstructing positionwhere the shutters 52 define a passageway 54 which is smaller than thesize of the passageway 54 defined when the shutters 52 are in the openposition. For instance, FIG. 1C illustrates the shutters in anobstructing position where the size of the passageway 54 approximatesthe size of the shaft 48 coupled with the wafer holder 38. Accordingly,the shutter 52 can be in an obstructing position while the wafer holder38 is positioned within the heating chamber 18. The configurationillustrated in FIG. 1C is the preferred configuration for the apparatus10 during the treatment of the wafer 28.

Treatment of the wafer 28 can include delivering a fluid, a gas or aliquid to the wafer 28 in the heating chamber 18. The obstructingposition of the shutter 52 illustrated in FIG. 1C can serve to reduceand even prevent entry of the fluids from the heating chamber 18 intothe cooling chamber 32. Accordingly, the shutters 52 can prevent thesefluids from fouling mechanisms in the cooling chamber 32 or in anassociated load/lock chamber.

The shutter 52 can also be constructed to act as a thermal insulator.When the shutter 52 is constructed as an insulator and the shutter 52 isin an obstructing position, the shutter 52 serves to increase thethermal isolation of the heating chamber 18 and the cooling chamber 32.The increased thermal isolation allows for an increased temperaturedifference between the average temperature in the heating chamber 18 andthe average temperature in the cooling chamber 32. Specifically, theratio of the average temperature in the heating chamber 18 to theaverage temperature in the cooling chamber 32 can be higher than itcould be without the shutter 52. As a result, the wafer 28 can be heatedand/or cooled more quickly than would be possible without the shutter52. The increased thermal isolation also reduces the amount of energyrequired to keep the average temperature in the heating chamber 18 andthe cooling chamber 32 within a certain range.

When the shutter 52 acts as a thermal insulator, the shutter 52 alsoserves to decrease the temperature drop between the shutter 52 and theheating plate 26. Accordingly, the temperature adjacent the top of theshutter is closer to the hot plate temperature than could be achievedwithout the shutter 52. As a result, the temperature in the heatingchamber 18 approaches isothermal which gives rise to improvedcontrollability of wafer temperature and run-to-run repeatability.Further, the near isothermal nature of the heating chamber 18 results infewer cold spots being formed in the heating chamber 18. The reductionin cold spots improves the thermal uniformity in the plane of the wafer28 and between the top and bottom of the wafer 28.

While FIGS. 1A-1C each illustrate the apparatus 10 including a shutter52, certain embodiments of the invention will not include a shutter 52.

FIG. 2A illustrates another embodiment of the heat treatment apparatus10. The heating plate 26 and processing tube 24 are independent of oneanother. The heating plate 26 is positioned between the processing tube24 and the heating elements 20. Accordingly, the heating plate 26 servesto provide a more even thermal distribution than can be provided by theprocessing tube 24 alone.

FIG. 2B illustrates another embodiment of an apparatus 10 where theheating plate 26 and the processing tube 24 are independent of oneanother. The heating plate 26 is positioned inside the processing tube24 so the heating plate 26 serves as the upper end 22 of the heatingchamber 18. Accordingly, heat from the heating elements 20 passesthrough the processing tube 24 before being distributed by the heatingplate 26. The heating plate 26 can sit flush against the processing tube24 or an air gap can be formed between the processing tube 24 and theheating plate 26. Other embodiments of the apparatus 10 do not include aheating plate 26. Similarly, the cooling source can be eliminated fromcertain embodiments of apparatus 10 such as the embodiment of theapparatus 10 illustrated in FIG. 1C.

As illustrated in FIG. 3, the cooling source can include a plurality ofcooling fluid conduits for delivery of a cooling fluid. The coolingfluid conduits can be directed so as to be pointed toward the surface ofwafer 28 within the cooling chamber 32 or can deliver the cooling fluidinto the cooling chamber 32 at a location which is remote from the wafer28.

Alternatively, the cooling fluid conduit can be shaped as a loop with aperimeter exceeding the perimeter of the wafer holder 38. The loopshaped cooling fluid conduit can be positioned in the cooling chamber 32so the wafer holder 38 can move through the cooling fluid conduit whenthe wafer holder 38 is carrying a wafer 28. Additionally, the loopshaped cooling fluid conduit can have cooling fluid ports arrangedaround the perimeter of the loop. The cooling fluid can be deliveredconcurrently from a plurality of different cooling fluid ports toachieve a shower of cooling fluid onto a wafer 28 within the coolingchamber 32. The shower effect provides a more uniform cooling to a wafer28 than is achievable with discrete cooling fluid conduits.

Although FIG. 3 illustrates a cooling fluid conduit used without acooling plate 42, one or more cooling fluid conduits can be used inconjunction with a cooling plate to increase the temperature ramp downof a wafer 28.

As described above, treatment of a wafer 28 in the wafer holder 38 caninclude delivery of a fluid to a surface of a wafer 28 in the heatingchamber 18. The following discussion discloses a variety of fluiddelivery systems. Each of the apparatuses 10 illustrated above can beadapted for use with the fluid delivery systems described below.Additionally, the above discussion illustrates that the upper end 22 ofthe heating chamber 18 can be defined by a heating plate 26 or by theprocessing tube 24. As a result, the upper end 22 of the heatingchambers 18 illustrated below can be defined by a heating plate 26 orthe processing tube 24.

FIG. 4A provides a bottom view of the upper end 22 of a heating chamber18. The upper end 22 of the heating chamber 18 includes a plurality offluid ports 70. These fluid ports are formed in the heating plate 26 orin the processing tube 24 depending on whether the processing tube 24 orthe heating plate 26 serves as the upper end 22 of the heating chamber18. The fluid ports 70 are in fluid communication with one or more fluidsources. The fluid from these fluid sources can be delivered into theheating chamber 18 and/or the cooling chamber 32 through the fluid ports70. The position of the fluid ports 70 over the wafer 28 permits adownward flow of fluid from the fluid ports 70 onto the wafer 28. Anexhaust conduit (not illustrated) can be positioned in either thecooling chamber 32 or in the heating chamber 18 for removing the fluiddelivered into the heating chamber 18. A fluid exhaust conduit ispreferably positioned near the bottom of the heating chamber 18 so as tobe below the wafer 28 during the treatment of the wafer 28. Thisposition of the fluid exhaust port 93 relative to the wafer 28 duringtreatment of the wafer 28 causes the fluid delivered from fluid ports 70in the heating plate 26 to flow downward over the surface of the wafer28 to the fluid exhaust port.

The fluid ports 70 can be evenly distributed across the upper end 22 ofthe heating chamber 18 as illustrated in FIG. 4A. For instance, thefluid ports 70 can be arranged in one of several different latticepatterns or in concentric geometric shapes. This even distribution ofthe fluid ports 70 encourages uniform fluid delivery across the plane ofthe wafer 28 and can encourage a plug type flow of the fluid from theupper end 22 of the heating chamber 18 toward the wafer 28. Thisuniformity can be vital in processes such as chemical vapor depositionwhere a non-uniform distribution of fluids across the wafer 28 canresult in uneven deposition results. The number of fluid ports 70 in theheating plate 26 is preferably from 0 to 1000, more preferably from200-800 and most preferably 550-650. The distance between adjacent fluidports 70 is preferably between 0.0 and 0.5 inches and is more preferablybetween 0.1 and 0.4 inches.

FIG. 4B provides a cross section of the upper end 22 of a heatingchamber 18 having a plurality of fluid ports 70. The fluid ports 70 arecoupled with a conduit 80 formed in the heating plate 26. The conduit 80terminates at a fixture 82 which is configured to be coupled with afluid conduit. The fluid conduit can be used to transport fluids intothe heating chamber 18 through the fluid ports 70 and/or can be used towithdraw fluid from the heating chamber 18 through the fluid ports 70.

FIG. 4C illustrates another embodiment of the upper end 22 of a heatingchamber 18. The fluid ports 70 extend through the portion of theprocessing tube 24 defining the upper end 22 of the heating chamber 18.An external lumen 84 is coupled with the top of the upper end 22 of theheating chamber 18 such that the lumen is in fluid communication witheach fluid port 70.

The fluid ports can be divided into a first group of fluid ports 70 anda second group of fluid ports. The first group of fluid ports 70 can bein fluid communication with a first fluid conduit and the second groupof fluid ports 70 can be in fluid communication with a second fluidconduit which is independent of the first fluid conduit. Differentfluids can be delivered through the first fluid conduit and the secondfluid conduit. As a result, a different fluid can be delivered from thefirst group of fluid ports 70 than is delivered from the second group offluid ports 70. Alternatively, the first fluid conduit can be used todeliver fluid into the heating chamber 18 while the second fluid conduitis used to withdraw fluid from the heating chamber 18.

FIG. 5A illustrates a fluid delivery system where the heat treatmentapparatus 10 includes a fluid inlet conduit 88 terminating in a fluidinlet port 90 and a fluid exhaust conduit 92 terminating in a fluidexhaust port 93. The fluid inlet port 90 and the fluid exhaust port 93can be positioned anywhere within the heating chamber 18. However, thefluid inlet port 90 and the fluid exhaust port 93 are preferably at aheight which allows them to be above the surface of the wafer 28 duringtreatment of the wafer 28. This position of the fluid inlet port and thefluid exhaust port permits the fluid to be flowed from the fluid inletport 90 to the fluid exhaust port 93 across the surface of the wafer 28.Accordingly, a fluid flow region is defined between the wafer and theupper end of the heating chamber during treatment of the wafer.

As illustrated in FIG. 5B a fluid inlet port 90 can be positioned abovethe wafer 28 during treatment of the wafer 28 and a fluid exhaust port93 can be positioned below the wafer 28 in the heating chamber 18 orwithin the cooling chamber 32. This position of the fluid inlet port 90relative to the fluid exhaust port 93 creates a downward fluid flow inthe heating chamber 18. Alternatively, the fluid conduits can beoperated in reverse so the fluid exhaust port 93 is above the wafer 28during treatment of the wafer 28 and the fluid inlet port 90 is belowthe wafer 28 during the treatment of the wafer 28.

FIG. 6A illustrates a heating chamber 18 which includes a flowcontainment member 94 extending inward from the side of the processingtube 24. As illustrated a wafer 28 can be positioned in the heatingchamber 18 so the wafer 28 and the flow containment member 94 define alower side of a fluid flow region 96 within the heating chamber 18.Suitable materials for the flow containment member 94 include, but arenot limited to, high purity quartz, fused silica and silicon carbide.The flow containment member 94 can be integral with the processing tube24 or can be an independent piece attached to the processing tube 24with techniques such as welding.

FIG. 6B is a cross sectional view of processing tube 24 looking downwardinto the heating chamber 18 at the axis labeled A in FIG. 6A. An inneredge 98 of the flow containment member 94 has a shape complementary tothe shape of a portion of the wafer perimeter. Additionally, the inneredge 98 of the flow containment member 94 is larger than the portion ofthe wafer perimeter to which the inner edge is complementary. Thedifference in the perimeter size of the wafer 28 and the perimeter sizeof the inner edge 98 of the fluid containment plate allows a wafer 28 tobe positioned adjacent to the flow containment member 94 with a gap 100formed between the wafer 28 and the inner edge 98 of the flowcontainment member 94. This gap 100 provides a route where fluidsdelivered into the fluid flow region 96 can escape the fluid flow region96. An auxiliary fluid exhaust conduit 102 with an auxiliary fluidexhaust port 104 can optionally be positioned below the flow containmentmember 94 in order to evacuate fluids which escape from the fluid flowregion 96 from the heating chamber 18.

The flow containment member 94 is sized to provide a gap 100 whichreduces escape of the fluids from the fluid flow region 96 into theremaining portions of the heating chamber 18.

During delivery of fluid into the heating chamber 18, the wafer 28 ispreferably positioned adjacent to the flow containment member 94. Thefluid flow region 96 limits the volume of atmosphere within the heatingchamber 18 which must be controlled during the treatment of the wafer28. Since atmospheric conditions are easier to control in a small volumethan in a larger volume, the atmospheric conditions are easier tocontrol in the fluid flow region 96 than would be possible to achieve inthe entire heating chamber 18. For instance, uniformity of temperatureis easier to control in a small volume than in a large volume.Accordingly, the fluid flow region 96 allows for a more easilycontrolled temperature.

The fluid flow region 96 can simplify the process of changing gasseswithin the heating chamber 18 while reducing interaction between thegasses. The fluid flow region 96 preferably has a substantially constantdistance between the bottom side of the fluid flow region 96 and theupper end 22 of the heating chamber 18. The constant distance encouragesa plug flow pattern for the fluid flowing from the fluid inlet conduitto the fluid exhaust conduit. A plug flow pattern allows one gas tofollow another gas with only minimal interaction of the two gasses. As aresult, fluids within the fluid flow region 96 can be changed by flowinga fluid through the fluid flow region 96, terminating the flow of thatfluid and concurrently starting the flow of another fluid through thefluid flow region 96. To further reduce interaction between the fluids,there can be a time delay between terminating the flow of the firstfluid and commencing the flow of the second fluid.

Although, FIGS. 6A-6B illustrate a single fluid exhaust conduit 92having a single fluid exhaust port 93 and/or a single fluid inletconduit 88 with a single fluid inlet port 90, the apparatus 10 caninclude a plurality of fluid inlet conduits 88 and/or a plurality offluid exhaust conduits 92. Further, a single fluid inlet conduit 88 canhave a plurality of fluid inlet ports 90. Additionally, the apparatus 10can include a plurality of fluid exhaust conduits 92 and a single fluidexhaust conduit 92 can include a plurality of fluid exhaust ports 93.Increasing the number of fluid conduits and the number of fluid ports inan apparatus 10 permits a greater degree of control over the conditionsof the fluid at the surface of the wafer 28.

FIG. 6C is a cross sectional view of a rectangular shaped processingtube 24 looking downward into the heating chamber 18 at the axis labeledA in FIG. 6A. The apparatus 10 includes a plurality of fluid inlet portspositioned above a flow containment member 94. Each fluid inlet port isaligned with a fluid exhaust port on an opposite side of the fluid flowregion 96. The plurality of fluid inlet ports and fluid exhaust portscan increase the plug flow characteristic of the fluid flow across thesurface of the wafer 28.

FIG. 6D illustrates an apparatus 10 having a plurality of flowcontainment members 94 arranged on opposing sides of the heating chamber18. The inner edge 98 of each flow containment member 94 has a shapecomplementary to the shape of a portion of the wafer perimeter.Additionally, the inner edge 98 of each flow containment member 94 islarger than the portion of the wafer perimeter to which the shape iscomplementary. As a result, each flow containment member 94 can bepositioned adjacent a portion of a wafer 28 with a gap 100 formedbetween the wafer 28 and the inner edge 98 of the flow containmentmember 94.

FIG. 7A illustrates a flow distribution member 106 positioned betweenthe flow containment member 94 and the wall of the processing tube 24. Aflow distribution member 106 is associated with the fluid inlet conduitand a flow distribution member 106 is associated with the fluid exhaustconduit. The flow distribution member 106 can be positioned at the inneredge 98 of the flow containment plate or can be closer to the wall ofthe processing tube 24. FIG. 7B is a sideview of a flow distributionmember 106. A plurality of holes 108 are formed through the flowdistribution member 106. The holes 108 preferably have a diameterbetween 0.01-0.1 inches, more preferably between 0.15-0.05 inches andmost preferably between 0.02-0.03 inches. The holes 108 are preferablyspaced to achieve a plug type flow from the flow distribution member.The holes 108 can have different sizes to encourage a more even flow.For instance, the holes 108 directly in front of the fluid inlet portcan have a smaller diameter than the holes 108 at the periphery of thefluid inlet port. The smaller diameter encourages a flow of fluid to theholes 108 at the periphery. Other embodiments of flow distributionmembers 106 include, but are not limited to mesh screens and wire grids.The number, size and arrangement of the holes 108 in a flow distributionmember 106 associated with a fluid inlet conduit can be the same as ordifferent from the number of holes 108 in a flow distribution member 106associated with a fluid exhaust conduit.

The wall of the processing tube 24 and the flow distribution member 106act together to form a fluid flow distribution chamber 110 around afluid inlet port. The flow distribution chamber 110 increases the areafrom which fluid enters the fluid flow region 96 over the area whichwould be possible without the flow distribution chamber 110. A flowdistribution chamber 110 can also be formed around a fluid exhaust port.A flow distribution chamber 110 around a fluid exhaust port can serve tospread out the flow of fluid leaving the fluid flow region 96. As aresult, this flow distribution chamber can prevent the fluid within thefluid flow region 96 from converging at the fluid exhaust port. Theeffect of the flow distribution chambers 110 formed around the fluidinlet port and the fluid chamber formed around the fluid exhaust port isto increase the plug flow characteristics of the fluid flow across thesurface of the wafer 28.

A flow distribution chamber 110 can also be constructed in differentways. For instance, the flow distribution chamber 110 can be filled witha porous media or diffusing material such as metal chips.

FIG. 7C is a cross sectional view of a processing tube 24 having arounded cross section. The flow distribution chamber 110 around thefluid inlet port and the flow distribution chamber 110 around the fluidexhaust port have are shapes. Although the flow distribution chambers110 are illustrated as arcing over a 180° range, flow distributionchambers 110 arcing over smaller angular ranges are also contemplated.

FIG. 7D illustrates a processing tube 24 with a rounded cross sectionand flow distribution members 106 with a straight contour. This geometryhas the advantage that the flow distribution chambers 110 areequidistant along their length. As a result, the distance a fluidtravels between the flow distribution chambers 110 is more uniform thanis possible when the flow distribution member 106 has a curved contour.The increased uniformity can increase the similarity between the fluidflow conditions experienced by the center of the wafer 28 and theconditions experienced at the edge of the wafer 28 midway between thetwo flow distribution chambers 110.

FIG. 7E is a cross sectional view of a processing tube 24 having arectangular cross section. The flow distribution members 106 both have astraight contour. This geometry has the advantages associated with flowdistribution chambers 110 which are equidistant along their length.

Although FIGS. 7A-7E each illustrate a single fluid inlet port and asingle fluid exhaust port associated with each flow distribution chamber110, each flow distribution chamber 110 can be associated with aplurality of fluid inlet ports and/or a plurality of fluid exhaustports.

As illustrated in FIG. 8, the flow distribution chamber 110 can bepartially defined by a second flow containment member 94 extendinginward from the side of the processing tube 24. The flow distributionmember 106 is positioned between the flow containment member 94 and thesecond flow containment member 94. The second flow containment member 94can optionally include a recess sized to receive the edge of a heatingplate 26. As a result, the second flow containment member 94 can supportthe heating plate 26. The heating plate 26 can sit flush against theprocessing tube 24 or an air gap can be formed between the processingtube 24 and the heating plate 26.

A single heating chamber 18 can include several flow distributionchambers 110 positioned at different heights. As a result, a wafer 28can be treated at different distances from the upper end of the heatingchamber 18.

FIG. 9A provides a cross section of a heat treatment apparatus 10 havingan enlarged fluid inlet port and an enlarged fluid exhaust port. Duringtreatment of a wafer, the wafer is preferably positioned adjacent thelowest point of the fluid inlet port. A portion of the fluid inletconduit, the fluid flow region and a portion of the fluid exhaustconduit combine to form a fluid flow passage 112 with a substantiallyconstant cross sectional geometry extending through the portion of thefluid inlet conduit, the fluid flow region and the portion of the fluidexhaust conduit. The substantially constant cross sectional geometrymeans the fluid flow pattern in one portion of the flow passage 112 issubstantially retained through the flow passage 112. This allows theflow pattern in the fluid inlet port to be retained across the fluidflow region. As a result, when a plug type flow is created in the fluidinlet port, the plug type flow is substantially retained through thefluid flow region.

FIG. 9B is a cross section of the processing tube 24 looking down intothe tube at the axis marked A and FIG. 9C is a cross section of theprocessing tube 24 looking up into the processing tube 24 at the axismarked B. The fluid flow region 96 is partially defined by flow regiondefining walls 114 positioned on opposing sides of the flow region. Theflow region defining walls 114 can have a variety of positions relativeto the fluid inlet conduit and the fluid exhaust conduit. For instance,FIG. 9D is a cross section of a processing tube 24 where the flow regiondefining walls 114 are sized to separate the fluid inlet conduit fromthe fluid exhaust conduit.

A flow distribution member 106 is positioned within the fluid inletconduit. Similarly, a flow distribution member 106 is positioned withinthe fluid exhaust conduit. As a result, a flow distribution chamber 110is formed within the fluid inlet conduit and within the fluid exhaustconduit. The flow distribution members 106 can be positioned at thefluid inlet port or along the length of the fluid inlet conduit.Similarly, a flow distribution member 106 can be positioned at the fluidexhaust port or along the length of the fluid exhaust conduit. The flowdistribution members 106 serve to spread the fluid flow out over thewidth of the fluid inlet conduit and/or the fluid exhaust conduit. As aresult, the flow distribution members 106 encourage a plug type flow inthe fluid flow passage 112.

The fluid inlet conduit and the fluid exhaust conduit have a shapematched to the shape of the fluid flow region 96. As illustrated, thefluid flow region 96 has a width about the width of the wafer 28. As aresult, the fluid inlet conduit and the fluid exhaust conduit havewidths, W, on the order of the wafer diameter. Similarly, the fluid flowregion 96 has a thickness about the thickness of the fluid inlet port.As a result, the fluid inlet conduit and the fluid exhaust conduit havea thickness, T, which approximates the thickness of the fluid inletport. The consistent shapes of the fluid inlet conduit, the fluid flowregion 96 and the fluid exhaust conduit allows the fluid to retain asimilar flow pattern in each of the fluid inlet conduit, the fluid flowregion 96 and the fluid exhaust conduit. As a result, the fluid flowpattern at the wafer surface can be controlled by controlling the fluidflow pattern in the fluid inlet conduit.

Although illustrated as being integral with the process tube, a fluidinlet conduit and a fluid exhaust conduit can have shapes matched to thefluid flow region 96 and can be independent of the processing tube 24.

A single processing tube 24 can include a combination of the above fluiddelivery systems. For instance, a single apparatus 10 can include fluidports 70 arranged in a heating plate 26, a fluid inlet conduit 88 and afluid exhaust conduit 92 positioned on opposing sides of a fluid flowregion 96.

FIG. 10A provides a sideview of shutters 52 designed to provide thermalinsulation. The shutter 52 is constructed from a plurality of members116. Suitable materials for constructing these members 116 include, butare not limited to, quartz covered insulators, silicon carbide andopaque fused silica. The members 116 are arranged to at least partiallydefine open air gaps 118 between adjacent members 116. Because air has alow thermal conductivity, these open air gaps 118 add thermallyinsulative properties to the shutter 52.

The open air gaps 118 have a height which is preferably slightly largerthan the thickness of each member 116. The open nature of the air gaps118 allows the shutters 52 to be meshed together as illustrated in FIG.10B. Specifically, a portion of one shutter 52 is slidably receivedwithin a portion of another shutter 52. When one shutter 52 is slidablyreceived in another shutter 52, the members of the opposing shutters 52preferably do not touch one another in order to avoid the production ofparticulates in the heating chamber 18.

FIG. 11A provides a topview of the shutters 52 when they are positionedin the obstructing position illustrated in FIG. 1C. The shutters 52include recesses 120 which have a geometry matched to the size and shapeof the shaft 48 coupled with the wafer holder 38. Accordingly, when thewafer holder 38 is positioned in the heating chamber 18 the shutters 52can be moved together so they form a passageway 54 with a shapeapproximating the shape of the shaft 48. Because the passageway 54 has ashape which is complementary to the shaft 48, the shaft 48 fits snuglywithin the passageway 54 to reduce exchange of gasses between theheating chamber 18 and the cooling chamber 32 and to reduce radiativeheat transfer from the heating chamber 18 to the cooling chamber 32.This shape can also serve to reduce radiative heat transfer from theheating chamber 18 to the cooling chamber 32.

FIG. 11B provides a topview of the shutters 52 when they occupy anobstructing position such as the position of the shutters 52 illustratedin FIG. 1A. The shutters 52 are slid far enough together to effectivelyclose the passageway 54. When the wafer holder 38 is positioned withinthe cooling chamber 32, the passageway 54 can be closed to increase thethermal isolation of the cooling chamber 32 and the heating chamber 18.Accordingly, the shutter configuration of FIG. 11B is desirable when thewafer holder 38 is positioned in the cooling chamber 32.

FIG. 11C illustrates a single shutter 52 which can be used to define thesize of the opening. The single shutter 52 includes a deep recess 120which receives the shutter 52 when the shutter 52 is positioned in anobstructing position and the wafer holder 38 is positioned within theheating chamber 18. The recess 120 is preferably deep enough that theshutter 52 can extend across the passageway 54 between the coolingchamber 32 and the heating chamber 18 when the wafer holder 38 ispositioned within the heating chamber 18. Although not illustrated, therecess 120 can include a lining made from a material which closes therecess 120 after the shaft 48 has been received within the recess 120.Suitable materials for lining the recess 120 include, but are notlimited to, rubber.

The shutters 52 illustrated in FIGS. 11A-11C include a single recess 120for accommodating a shaft 48 coupled with the wafer holder 38; however,the shutters 52 can include a plurality of recesses 120 foraccommodating a plurality of shafts 48 coupled with a wafer holder 38.

Although the shutters 52 illustrated above are constructed from aplurality of members 116, each shutter 52 can be constructed from asingle member 116. Additionally, each passageway 54 illustrated above isconstructed from two shutters 52; however, the apparatus 10 can includethree or more shutters 52 which define a single passageway 54.

FIGS. 12A-12D illustrate possible arrangements for the heating elements20 used with the apparatuses 10 disclosed above. The heating elements 20are each arranged in concentric heating zones 122. The heating elements20 in a particular heating zone 122 can be arranged in concentriccircles as illustrated in FIG. 12A. Alternatively, a single heatingelement 20 with a rounded geometry can occupy a heating zone 122 asillustrated in FIG. 12B. The heating elements 20 in different heatingzones 122 are preferably controlled independently. When multiple heatingelements 20 are included in a particular heating zone 122, the heatingelements 20 can be eclectically connected in series or in parallel orcan be independently controlled.

Thermal isolation barriers 124 can be positioned between the heatingzones 122 as illustrated in FIG. 12C. As illustrated in FIG. 12D, thethermal isolation barriers 124 can extend from the thermal insulator 16toward the processing tube 24 and can be coupled to the processing tube24. In another embodiment, the thermal isolation barriers 124 extendfrom the insulation toward a heating plate 26 and can be coupled to theheating plate 26.

The thermal isolation barriers 124 can reduce the cross talk of the heatproduced by the heating elements 20 in different heating zones 122. As aresult, the heat produced in a particular heating zone 122 is directedtoward the heating plate 26 or the processing tube 24. Accordingly,adjustments made to a particular heating element 20 affect primarily theportion of the heating plate 26 or the processing tube 24 which areadjacent the adjusted heating element 20. As a result, the thermalisolation barriers 124 serve to increase the degree of control over thethermal conditions within the heating chamber 18. Although FIGS. 12A-12Dillustrate a processing tube 24 having a rounded cross section, theheating elements 20 and thermal isolation barriers 124 can be adapted toprocessing tubes 24 having a rectangular cross section.

FIG. 13 illustrates an apparatus 10 having a shaft conduit 126 extendingfrom the cooling chamber 32. The shaft conduit 126 encloses a portion ofthe shaft 48 extending below the cooling chamber 32. The shaft conduit126 can be integral with the frame of the cooling chamber 32 or can bean independent piece which is attached to the frame of the coolingchamber 32. Any of the apparatuses 10 disclosed above can be adapted foruse with the shaft conduit 126.

A seal 128 is formed between the shaft conduit 126 and the shaft 48 at aposition which is remote from the cooling chamber 32. The seal 128serves to reduce the escape of fluids from the cooling chamber 32 and/orto reduce the entry of fluids from the atmosphere into the coolingchamber 32. As a result, the seal 128 helps to increase the thermal andphysical isolation of the cooling chamber 32 from the atmosphere. Thisisolation enhances the controllability of the atmosphere within thecooling chamber 32.

The remote location of the seal 128 reduces the heat to which the seal128 is exposed. For instance, while the wafer 28 is positioned withinthe heating chamber 18, the portion of the shaft 48 within the heatingchamber 18 heats up. However, lower portions of the shaft 48 retaincooler temperatures because they are nearer the cooling chamber 32and/or because they spend less time in the heating chamber 18. Theposition of the seal 128 remote from the cooling chamber 32 results inexposure of the seal 128 to lower portions of the shaft 48 than wouldoccur if the seal 128 were within or adjacent to the cooling chamber 32.As a result, the position of the seal 128 remote from the coolingchamber 32 can serve to protect the seal 128 from heat damage and canaccordingly preserve the seal 128. The distance of the seal 128 awayfrom the cooling chamber 32 is preferably equal to about the maximumdistance which the shaft 48 extends into the heating chamber 18.

A seal 128 can be formed at the junction of the cooling chamber 32 andthe shaft 48. Such a seal 128 is an alternative to, or can be used inconjunction with, the seal 128 between the shaft 48 and the shaftconduit 126.

The invention also relates to a method of operating the apparatus 10.During operation of the heat treatment apparatus 10 the wafer holder 38can be positioned anywhere within the heating chamber 18 during the rampup of the wafer 28 temperature. However, the wafer 28 is preferablypositioned so close to the heating plate 26 that heat is conducted tothe wafer 28 through the air between the heating plate 26 and the wafer28. Because the wafer 28 is also receiving the heat rays radiated fromthe heating plate 26, the close proximity of the wafer 28 and theheating plate 26 causes the wafer 28 to be concurrently heated by bothradiation and conduction. These two heat transfer mechanisms provide anaccelerated temperature ramp up.

During temperature ramp up and when the wafer 28 is close enough to theheating plate 26 for conduction to occur, the percentage of heattransferred to the wafer 28 by conduction is preferably 30-90%, morepreferably between 40-80% and most preferably between 50-70%. During thetemperature ramp up the wafer 28 is preferably positioned within 2 mm ofthe heating plate 26 and more preferably within 1 mm of the heatingplate 26. However, the distance between the wafer 28 and the heatingplate 26 which is required to achieve a particular degree of heattransferred by conduction is a function of the temperature at theheating plate 26. For instance, when the temperature of the heatingplate 26 is approximately 900° C., the wafer 28 is preferably positionedwithin 2 mm of the heating plate 26. However, when the temperature ofthe heating plate 26 is approximately 500° C., the wafer 28 ispreferably positioned within 0.8 mm of the heating plate 26. Thedistance between the wafer 28 and the heating plate 26 can be variedduring treatment of the wafer in order to control the heating rate. Forinstance, the ramp up rate can be increased by moving the wafer closerto the heating plate 26.

FIG. 14 illustrates the heat flux due to radiation compared with theheat flux due to conduction at two different displacements of the waferfrom the heating plate 26. As illustrated, the percentage of heat fluxfrom conduction increases with proximity of the wafer to the heatingplate 26. For instance, at 900° C. and 0.2 mm from the heating plate 26,the heat flux due to conduction is about two thirds of the total heatflux. However, at 900° C. and 1 mm from the heating plate 26, the heatflux due to conduction is reduced to about one third of the total heatflux. As a result, a wafer must be placed in close proximity to theheating plate 26 in order to obtain the benefits of conductive heatflux.

Once a target condition has been achieved at the wafer 28, the wafer 28can be treated. For instance, once the wafer 28 reaches a targettemperature, a fluid can be delivered into the heating chamber 18.Alternatively, once the target condition has been achieved at the wafer28, the wafer 28 can be backed away from the heating plate 26. Backingthe wafer 28 away from the heating plate 26 can serve to move the wafer28 under a fluid inlet port 90 coupled with a fluid inlet conduit 88 orcan provide improved flow characteristics of a fluid over the wafer 28by increasing the clearance between the wafer 28 and the heating plate26.

During treatment of the wafer 28, the wafer 28 can be rotated byrotating the wafer holder 38. When the wafer 28 is rotated, the wafer 28is preferably rotated at 0 to 600 r.p.m. and more preferably at 5 to 15r.p.m. The rotation of the wafer 28 can serve to provide a more uniformexposure of the wafer 28 to fluids delivered into the heating chamber 18during the treatment of the wafer 28. The rotation of the wafer 28 canalso provide a more uniform thermal budget.

Once the wafer 28 has been treated within the heating chamber 18, theshutters 52 can be opened and the wafer holder 38 can be lowered intothe cooling chamber 32. A target condition can then be achieved at thewafer 28 before the wafer 28 is removed from the wafer holder 38. Forinstance, the wafer 28 can be reduced to within a range of targettemperatures before the wafer 28 is removed from the wafer holder 38.

While the present invention is disclosed by reference to the preferredembodiments and examples detailed above, it is to be understood thatthese examples are intended in an illustrative rather than limitingsense, as it is contemplated that modifications and combinations willreadily occur to those skilled in the art, which modifications andcombinations will be within the spirit of the invention and the scope ofthe appended claims.

What is claimed is:
 1. A heat treatment apparatus, comprising: a heatingchamber having a heat source; a cooling chamber positioned adjacent tothe heating chamber and including a cooling source; a wafer holderconfigured to move between the cooling chamber and the heating chamberthrough a passageway positioned between the heating source and thecooling source, and one or more shutters defining the size of thepassageway and being movable between an open position where the waferholder can pass through the passageway and an obstructing position whichdefines a passageway which is smaller than the passageway defined whenthe shutter is in the open position, where said one or more shuttersincludes two shutters positioned on opposing sides of the passageway,the two shutters being movable toward and away from one another.
 2. Theapparatus of claim 1, wherein the heating source is a heating platepositioned adjacent to a plurality of heating elements, the heatingplate configured to receive heat from the heating elements andre-radiate heat into the heating chamber.
 3. The apparatus of claim 2,wherein a processing tube defines the heating chamber and the heatingplate is positioned outside the processing tube.
 4. The apparatus ofclaim 2, wherein the heating chamber is defined by a processing tubewhich includes the heating plate.
 5. The apparatus of claim 4, wherein apath from the heating plate to the wafer holder is unobstructed.
 6. Theapparatus of claim 1, wherein a processing tube defines the heatingchamber and an upper end of the processing tube includes a plurality offluid ports configured to deliver a fluid into the heating chamber. 7.The apparatus of claim 6, wherein the fluid ports are evenly distributedacross the closed upper end.
 8. The apparatus of claim 6, wherein thefluid ports are positioned such that a fluid delivered from the fluidports would be delivered onto a wafer held by the wafer holder from overthe wafer.
 9. The apparatus of claim 6, wherein a first plurality of thefluid ports are coupled with a first fluid conduit and a secondplurality of fluid ports are coupled with a second fluid conduit. 10.The apparatus of claim 1, wherein the cooling source is positionedadjacent to a bottom of the cooling chamber.
 11. The apparatus of claim1, wherein the cooling source is positioned beneath the lowest positionthat the wafer holder can occupy within the cooling chamber.
 12. Theapparatus of claim 1, wherein the cooling source includes a coolingfluid conduit for delivering a cooling fluid into the cooling chamber.13. The apparatus of claim 1, wherein the cooling source is a coolingplate having one or more conduits for transporting a cooling fluidthrough the cooling plate.
 14. The apparatus of claim 1, wherein thecooling source is a cooling plate positioned adjacent to one or moreconduits configured to carry cooling fluid.
 15. The apparatus of claim1, wherein the cooling source is a cooling plate including one or moreapertures, each aperture configured to slidably receive a shaft whichsupports the wafer holder.
 16. The apparatus of claim 1, wherein thecooling source is a cooling plate positioned approximately concentricwith wafers held by the wafer holder.
 17. The apparatus of claim 1,wherein the cooling source is a cooling plate with an upper surfacehaving a surface area exceeding the surface area of a bottom surface ofa typical wafer to be held by the wafer holder.
 18. The apparatus ofclaim 1, wherein the wafer holder is configured to hold the wafer so thewafer can be positioned within 2 mm of the heating source.
 19. Theapparatus of claim 1, wherein no portion of the wafer holder extendsabove a wafer being held by the wafer holder.
 20. The apparatus of claim1, wherein the one or more shutters is configured to slide in asubstantially horizontal plane.
 21. The apparatus of claim 1, whereinthe one or more shutters is constructed from a thermal insulator. 22.The apparatus of claim 1, wherein the one or more shutters areconfigured to occupy an obstructing position when the wafer holder ispositioned within the heating chamber.
 23. The apparatus of claim 1,wherein a shaft supports the wafer holder and at least one of the one ormore shutters has a side with a recess, the recess having a shape whichis complementary to a cross sectional contour of the shaft.
 24. Theapparatus of claim 23, wherein the one or more shutters is configured tomove to an obstructing position where the shaft is accommodated withinthe at least one recess.
 25. The apparatus of claim 1, wherein at leastone of the one or more shutters includes two or more members positionedto define at least a portion of an air gap between adjacent members. 26.The apparatus of claim 25, wherein the two or more members areconstructed from a quartz covered thermal insulator.
 27. The apparatusof claim 1, wherein at least one of the one or more shutters can beslidably received within another of the one or more shutters.
 28. Theapparatus of claim 1, wherein a first shutter selected from the one ofthe one or more shutters can be slidably received within a second of theone or more shutters such that the first shutter and the second shutterdefine at least a portion of an air gap.
 29. The apparatus of claim 1,wherein the one or more shutters can occupy an obstructing positionwhich completely closes the passageway.
 30. The apparatus of claim 1,further comprising: one or more fluid inlet ports positioned to delivera fluid into the heating chamber.
 31. The apparatus of claim 30, whereina member extends into the heating chamber from a side of the heatingchamber at a height below a height of the fluid inlet port.
 32. Theapparatus of claim 30, wherein a member extends into the heating chamberfrom a side of the heating chamber at a height above a height of thefluid inlet port.
 33. The apparatus of claim 1, wherein a member extendsinto the heating chamber from a side of the heating chamber and iscoupled with a heating plate.
 34. The apparatus of claim 33, wherein themember supports the heating plate.
 35. The apparatus of claim 1, whereina member extends into the heating chamber from a side of the chamber,the member having an edge with a shape which is complementary to theperimeter of a portion of wafer to be treated in the apparatus.
 36. Theapparatus of claim 35, wherein a length of the edge is larger thanportion of the perimeter to which the edge is complementary.
 37. Theapparatus of claim 30, further comprising a flow distribution chamberwhich distributes a flow of fluid from the one or more fluid inletports, the flow distribution chamber positioned such that fluid from thefluid inlet port enters the heating chamber through the flowdistribution chamber.
 38. The apparatus of claim 1, further comprising aflow distribution chamber for distributing the flow of fluid from theone or more fluid inlet ports, the flow distribution chamber positionedsuch that fluid from the fluid inlet port enters the heating chamberthrough the flow distribution chamber.
 39. The apparatus of claim 1,further comprising: a fluid exhaust port for withdrawing fluid from theheating chamber; and a flow distribution chamber for distributing a flowof fluid from the heating chamber to the fluid exhaust port, the flowdistribution chamber positioned such that fluid from the heating chamberenters the fluid exhaust port through the flow distribution chamber. 40.The apparatus of claim 38, wherein the flow distribution chamberincludes a flow distribution member positioned between a wall of theheating chamber and a member extending into the heating chamber from aside of the heating chamber.
 41. The apparatus of claim 38, wherein theflow distribution chamber includes a flow distribution member positionedbetween a first member extending into the heating chamber from a side ofthe chamber and a second member extending into the heating chamber fromthe side of the heating chamber.
 42. The apparatus of claim 1, furthercomprising: one or more fluid inlet ports positioned to deliver a fluidinto the heating chamber; and one or more fluid exhaust ports positionedto withdraw a fluid into the heating chamber, the one or more fluidexhaust ports positioned such that a fluid flowing from the one or morefluid inlet ports to the one or more fluid exhaust ports flows acrossthe heating chamber.
 43. A heat treatment apparatus, comprising: aheating chamber having a heat source; a cooling chamber positionedadjacent to the heating chamber and including a cooling source; a waferholder configured to move between the cooling chamber and the heatingchamber through a passageway positioned between the heating source andthe cooling source; one or more shutters defining the size of thepassageway and being movable between an open position where the waferholder can pass through the passageway and an obstructing position whichdefines a passageway which is smaller than the passageway defined whenthe shutter is in the open position, where said one or more shuttersinclude two shutters positioned on opposing sides of the passageway, thetwo shutters being movable toward and away from one another; one or morefluid inlet ports positioned to deliver a fluid into the heatingchamber; one or more fluid exhaust ports positioned to withdraw thefluid from the heating chamber; a flow distribution chamber positionedsuch that the fluid from the fluid inlet ports is distributed to theheating chamber and the fluid from the heating chamber is distributed tothe exhaust ports through the flow distribution chamber; and one or moreflow containment members extending into the heating chamber from a sideof the heating chamber, the member having an edge with a shape which iscomplementary to a perimeter of a portion of a wafer supported in thewafer holder.